The present invention relates to a method for graphically displaying a sectional image through an object under examination having objects situated therein, in particular for the display of a sectional image through a building wall having obstacles situated therein, and a position finder that is designed accordingly.
In detecting the location of objects in a building wall, various possibilities for displaying the result of the location detection are known.
The simplest possibility provides only a light-emitting diode and/or a buzzer for indicating the result of the location detection, whereby a warning signal is sounded when the result measured by a position detector exceeds a threshold value. This method for indicating the result of the location detection only enables a statement to be made about possible obstacles in the current position of the position detector, however. Moreover, the operator receives no quantitative information about the maximum possible drilling depth. Instead, he only receives qualitative information as to whether or not an object is even located beneath the position detector.
It is further known that pointing devices, bar displays and/or buzzers with variable pitch may be used to indicate the result of the location detection, whereby the depth of an object located in a building wall determines the deflection of the pointer or bar, or the pitch. The operator is therefore also provided with quantitative information about the depth of a located object. In this case as well, however, the display of the result of the location detection only enables a statement about the permissible drilling depth at the current position of the position detector.
In addition, a graphic display of the result of the location detection on an LCD screen is known from the NJJ-85A position finder marketed by the Japanese company JRC Radio Corporation. In this case, the position finder sends a signal into the building wall and the signal is reflected by objects located therein. The depth of the located object can be calculated based on the delay time of the reflected signal after emission until it is received by the position finder. After a line section is measured out on the building wall, the amplitude of the reflected signal is depicted graphically as a function of the delay time and the position on the line section. The operator can then identify objects in the building wall based on maximum amplitudes that stand out from the rest, and he can calculate the depth of the objects based on the delay time. This method of displaying results requires a considerable amount of experience in identifying objects and subsequently calculating the depth of the objects, however.
Finally, a method for graphically displaying the results of a location detection is known from the HILTI Ferroscan locating device. With this device, the area of interest on the building wall is scanned in eight consecutive linear line sections measuring 60 cm each, and the position result of the individual linear scans is stored. After the scan is performed in two dimensions, a quasi-transparent view of the interior of the wall is displayed on an LCD screen. The depth of each individual location must be queried separately. The operator does not receive any information about any objects at the current position of the position detector while he is performing the scanning function with the position detector, however. Instead, the operator must first generate the required position data in a complex procedure.